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For Senior Drivers, One Drink May Be One Too Many

Written by Alexia Severson
| Published on March 11, 2014

A new study finds that even low doses of alcohol may affect seniors' ability to course correct and maintain speed while driving.

If you think you’re safe drinking one glass of wine with dinner before hitting the road, think again. Just one serving of alcohol may be enough to impair driving ability in those 55 or older, a new study by researchers from the University of Florida (UF) has revealed.

While many studies have researched the effects of alcohol on younger drivers, this is the first to look at how even low doses of alcohol can affect senior drivers. The results of the study were published in the journal Psychopharmacology, and researchers say the findings could eventually lead to changes in legal blood alcohol levels for drivers of all ages. Currently, it is legal to drive with a blood alcohol content, or BAC, of below 0.08.

“Aging has changed in recent decades,” said Sara Jo Nixon, Ph.D., a professor of psychiatry at UF, in an interview with Healthline. “Older individuals are remaining active in both social and professional domains for longer periods of time. These environments often involve the opportunity for alcohol consumption. Yet, relatively little work has been directed to the study of the effects of alcohol among older, moderate drinkers.”

A Simulated Driving Experience

To explore the effects of moderate doses of alcohol on both older drivers (ages 55 to 70) and younger drivers (ages 25-35), Nixon and her team had a total of 36 people from each age group complete a simulated driving task. First, sober participants were asked to drive down a winding, quiet simulated two-lane road for about three miles with occasional oncoming traffic and few other distractions. Participants were surrounded by three separate computer monitors that mimicked the feeling of driving a vehicle, and they controlled the virtual car by using a steering wheel console, accelerator, and brake pedals.

During the simulated driving task, researchers observed specific driving skills commonly affected by alcohol consumption, including how quickly the driver attempted to adjust their lane position (steering rate), how well the driver was able to stay in the designated lane, their ability to maintain a constant speed, and the drivers' average speed throughout the task.

Later, participants in each age group were asked to complete the same task after being separated further into three different groups: The first group drank water, the second drank an alcoholic beverage strong enough to produce a BAC of 0.04, and the third group drank a beverage that produced a BAC of 0.065 percent. The experiment was meant to reflect a situation in which a person has a drink with dinner before driving home.

Researchers found that despite the participants' low BAC, just one serving of alcohol was enough to affect seniors' driving abilities. They found no significant signs of impaired driving among the younger moderately intoxicated drivers.

“In general, older adults performed more poorly on measures of driving precision and drove more slowly than younger adults prior to the consumption of alcohol,” study authors wrote. “Older adults also exhibited greater impairment as a result of alcohol consumption on two precision driving measures," they said, namely, steering rate and the ability to maintain a constant speed.

“Key skills essential to effective driving were compromised in the older group of drivers,” Nixon said.

However, more research is needed to fully understand the relationship between age and alcohol, as well as the real-world implications of these findings, researchers said.

Researchers are also evaluating other study results, including a scenario in which participants drove through more complex small-town and city settings, as well as examining data collected through scalp electrodes imbedded in caps worn by the moderately intoxicated drivers. The team also hopes to look at differences in the effects of alcohol consumption and aging on men and women.

Driving in the Real World

Each day, nearly "30 people in the U.S. die in motor-vehicle crashes that involve an alcohol-impaired driver,” according to the U.S. Centers for Disease Control and Prevention (CDC). In 2010 alone, more than 10,200 people “were killed in alcohol-impaired driving crashes, accounting for nearly one-third of all traffic-related deaths in the U.S.,” according to CDC statistics.

While the study by researchers at UF found that moderate consumption of alcohol did not affect young adults' driving in a simplified virtual setting, Nixon said that these findings do not mean that young drivers can’t be affected by low doses of alcohol under different circumstances. In fact, according to the CDC, young people at all BAC levels run a greater risk than older drivers of being involved in a crash while intoxicated.

“Alcohol can have effects on driving skills at lower doses than is typically presumed,” Nixon said. “Furthermore, these deficits may be sufficiently subtle that drinkers are not aware of them. Finally, the driving environment did not fully parallel driving in the real world. In the real world, there are many more on-going and unexpected distractions, which might exacerbate these effects in both age groups.”

The CDC recommends planning ahead before attending social events that involve alcohol by designating a non-drinking driver to take you and friends home, calling a taxi, or asking someone sober to pick you up.

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